Priming composition



Patented Dec. 29, 1936 mesne assignments, to Remington Arms Company, Inc., Bridgeport, Conn., a corporation of Delaware No Drawing.

Application September 9, 1931,

Serial No. 561,994. W In Great Britain September 19, 1930 4 Claims.

This invention relates to improved priming compositions for propellent cartridges, and it comprises priming compositions for percussion caps adapted for propellent cartridges, said priming composition comprising lead azide,

guanylnitrosaminoguanyl tetrazene and barium nitrate, as an oxidizing agent, and advantageously also comprising a fuel such as calcium silicide, and having improved properties including increased sensitiveness rendering them advantageous for use in percussion caps.

It has already been proposed to employ lead azide as an ingredient of percussion cap compositions, but its application has been limited. Against its use it has been urged that lead azide is dangerous to manufacture, has a low sensitiveness, and that compositions containing it are too violent in action: the addition of other ingredients customary in percussion cap manufacture, While slightly decreasing the violence of action, has a further deleterious effect upon the sensitiveness. The use of colloidal lead azide in place of the crystalline variety, whilst increasing safety in manufacture, results in a still less sensitive composition.

The advantages accruing from the use of the lead azide are as follows:-

(I) Increased safety in manufacturing operations due to the low sensitivity of the uncompressed compositions, which do not bear any exact relation in sensitivity to compositions as finally compressed in the cap shell.

(2) Economy, due firstly to the low cost of lead azide and the large proportions of cheap ingredients which may be used, and secondly to the low charge of the composition itself.

(3) The great stability of lead azide compositions.

(4) By replacing mercury fulminate, season cracking of the brass cartridge cases is eliminated.

I have discovered means by which priming compositions containing lead azide may be prepared so as to obtain all the normal advantages of its use While eliminating certain defects and disadvantages heretofore considered more or less fundamental and inherent in the use of lead azide.

I have now found that compositions containing lead azide both of the colloidal and crystalline varieties can be made to conform to specifications of sensitiveness by the inclusion of guanylnitrosamino-guanyl tetrazene, in the. mix. The violence of such compositions can be regulated as desired by the addition of fuels and oxidizing agents in suitable proportions without the deleterious effect upon the sensitiveness previously mentioned.

A priming composition adapted for percussion caps made in accordance with my present invention, comprises lead azide, guanylnitrosaminoguanyl tetrazene, barium nitrate (as an oxidizing agent) and, advantageously, a fuel such as calcium silicide.

When the lead azide content is low, for example between 5% and of the total mix, and the content of the other, and more inert, ingredients consequently high, a large proportion of guanylnitrosaminoguanyl tetrazene, for example from 10% to of the total mix, should be added to bring the sensitiveness of the final mix to the required level. If, on the other hand, the lead azide content is higher, for example between 15% and of the total mix, a smaller proportion of tetrazene, for example from 0.5% to 5% of the total mix, is sufiicient to sensitize the final mix.

The sensitivity of a cap composition depends partly on the hardness of the ingredients, and I find that in compositions that do not contain much hard material it is sometimes necessary to use a higher proportion of guanylnitrosaminoguanyl tetrazene together with a high proportion of lead azide.

Compositions containing lead azide and the higher proportions of guanylnitrosoaminoguanyl tetrazene have the great advantage over those containing low proportions of guanylnitrosaminoguanyl tetrazene of binding well and not breaking away under the pressing punches.

Typical cap compositions which may be used are the following:-

Per cent Per cent Lead azide 25.0 14.0 Barium nitrate 54.5 46.0 Calcium silicide 20.0 20.0 Guanylnitrosaminoguanyltetrazene 0.5 10.0 Lead peroxide 10.0

the composition is loaded in two layers. A layer of composition rich in lead azide is first introduced, and then a layer consisting of a fuel, such as calcium silicide, and an oxidizing agent tains a low total content of lead azide and functions through the lower layer exploding and disintegratingthe upper layer. The fuel and oxidizing agent in this layer, being in the form of an extremely "fine powder and very intimately mixed, produce a large flame.

Typical compositions for use in this manner areze ('1') Layer in base of cap shell r y Percent Lead azide 35 Barium nitrate 60 Guanylnitrosaminoguanyl tetrazene 1 (2) Upper layer Barium nitrate 50 "Calcium silicide 50 British usage of the term cap.

I do not restrict myself to any particular ingredients other than lead azide and guanylnitrosamino'guanyl tetra zene or to any particular method of mixing the ingredients.

There is a diiference between American and In the present specification'by the term cap I mean caps adapted for priming cartridges, that is, propellent'cartridges, and I do not intend to include detonators'for explosive shells, bombs or blasting explosives, in such terms.

such as barium nitrate, only. Such a cap contrate.

3; A primer for the ignition of the propellent powder of a small arms cartridge comprising a mixture of lead azide, guanylnitrosaminoguanyltetrazene and barium nitrate, and contiguous thereto a second mixture of calcium silicide and barium nitrate.

4. A primer for the ignition of the propellent powder of a small arms cartridge comprising a mixture of approximately 35% of lead azide, 5% of guanylnitrosaminoguanyltetrazene, and 60% of barium nitrate; and contiguous thereto a second mixture of approximately 50% of calcium silicide and 50% of barium nitrate.

ALFRED WEALE. 

